IR SPECTRAL ANALYSIS OF THE LIQUID FRACTION FROM POLYMER WASTE

ABSTRACT

This study focuses on analyzing the liquid fraction obtained from low-molecular-weight polymer waste (LMWPW) generated at the Shurtan Gas Chemical Complex. After vacuum filtration, 95% of the waste was collected as liquid, which was studied for its physical and chemical properties. The results showed that the liquid has low viscosity and is suitable for use as a base oil in plastic lubricants (PLMs). Infrared (IR) spectroscopy revealed the presence of long-chain alkanes and naphthenic hydrocarbons, with no corrosive functional groups detected. These findings suggest that LMWPW can be effectively reused to produce eco-friendly and cost-efficient lubricant components.

АННОТАЦИЯ

В данном исследовании рассматривается жидкая фракция, полученная из низкомолекулярных полимерных отходов (НМПО), образующихся на Шуртанском газохимическом комплексе. После вакуумной фильтрации около 95% отходов было выделено в виде жидкости, которая была исследована на физико-химические свойства. Результаты показали, что жидкость обладает низкой вязкостью и может быть использована в качестве базового масла при производстве пластичных смазочных материалов (ПСМ). Инфракрасная (ИК) спектроскопия выявила наличие длинноцепочечных алканов и нафтеновых углеводородов, при этом коррозионно-активные функциональные группы не обнаружены. Полученные данные свидетельствуют о возможности эффективного повторного использования НМПО для получения экологически безопасных и экономически выгодных компонентов смазочных материалов.

Keywords: low molecular polymer, waste, ecology, vacuum filter, fraction, plastic lubricant, dispersed medium, density, viscosity, IR spectrum, alkane, cycloalkane, polyalphaolefin.

Ключевые слова: низкомолекулярный полимер, отходы, экология, вакуумный фильтр, фракция, пластичные смазка, дисперсная среда, плотность, вязкость, ИК-спектр, алкан, циклоалкан, полиальфаолефин.

Introduction. Nowadays, one of the most pressing challenges facing the petrochemical industry is to find and increase resources that can replace oil, which serves as the primary and main source of fuel and lubricants produced both in the world and in our Republic. Additionally, there is a focus on processing or utilizing waste (by-products) from the oil and gas sector, as well as other industries, as substitutes or additional composites for products derived from oil and petroleum products. Furthermore, these activities not only achieve good economic efficiency by recycling waste and by-products but also help to reduce negative impacts on the environment and ecology [1].

In current work, alongside the production of finished products in the technological processes of the Shurtan Gas Chemical Complex, certain types of wastes are generated, including used activated carbon, used silica gel, waste from molecular sieves, waste from "yellow oil," used CRS-31 catalyst, used aluminum oxides, and low-molecular-weight polymer waste (LMWPW). The possibilities of using these wastes as compositions for plastic molding materials (PMM) have been analyzed. This is expected to expand the range of PMMs, increase their resources, enhance economic efficiency, and prevent harmful effects on the environment and ecology [2-3].

During the production of high-density polymer products at the Shurtan Gas Chemical Complex in our country, low-molecular-weight polymer waste (LMWPW) is generated. This waste is purified by dissolving it in cyclohexane solvent and can reach a volume of about 1200 tons per year, depending on the amount of produced polyethylene [4].

Research methodology. Low-molecular-weight polymer waste transported from the Shurtan Gas Chemical Complex underwent vacuum filtration (Fig. 1).

Figure 1. The image of LMWPW and its vacuum-filtered fractions: a) low-molecular polymer waste; b) polymer; c) filtrate-liquid fraction

The vacuum filtration process revealed that 5% by mass of the polymer (Figure 1.b) and 95% by mass of the liquid fraction (Figure 1.c) could be separated from the low molecular weight polymer waste (Figure 1.a).

The physicochemical properties of the polymer derived from low molecular weight polymer waste are as follows: a light brown color, solid form at 20°C, a density of 810,9 kg/m³ at 20°C, a liquidus temperature of 65°C, insolubility in water, and solubility in ether (as well as alcohol and arenes).

The physicochemical properties of the liquid fraction derived from low molecular weight polymer waste are as follows: a brown-yellow color, remains in liquid form at 20°C, a density of 953,5 kg/m³ at that temperature, and exhibits kinematic viscosities of 2,13, 2,10, and 1,39 mm²/h at 40, 50, and 100°C, respectively. The initial boiling point is 80,5°C, and it is insoluble in water while being soluble in ether (as well as alcohol and arenes).

The aim of this research is to explore the use of the filtered liquid fraction from low molecular weight polymer waste as a dispersion medium (base oil) for plastic molding materials. According to the literature, base oils used in producing plastic molding materials typically have low to medium viscosities (no more than 50 mm²/h at 50°C). Taking this into account, it is noted that the kinematic viscosity of the liquid fraction derived from low molecular weight polymer waste is below the established requirement.

Figure 2. Infrared (IR) spectrum image of the liquid fraction of low molecular weight polymer waste

An IR spectroscopic image (Fig. 2) has been obtained and analyzed to study the liquid fraction of low molecular weight polymer waste. Notably, the absorption signals in the IR spectrum located left of the wave number 1500 cm⁻¹, as this region is diagnostic and offers valuable insight into the substance. In Figure 2, the image of the liquid fraction shows significant IR absorption at wave numbers of 2957.60 cm⁻¹, 2920.33 cm⁻¹, and 2852.95 cm⁻¹. These peaks are found within the 3000 to 2840 cm⁻¹ range. According to references [5-7], these peaks are associated with hybridized carbon linked through carbon-hydrogen bonds as  . The absorption signal at 2957.60 cm⁻¹ is characteristic of variable intensity for alkanes and alkyls. A strong signal at 2920.33 cm⁻¹ is recognized as the  bond in naphthenic hydrocarbons. The peak at 2852.95 cm⁻¹, which has a moderate intensity, relates to the  bond in the alkane molecule. A weak signal at 2356.91 cm⁻¹ corresponds to the  triple bond, while the similar intensity signal at 1717.50 cm⁻¹ is linked to the  double bond. The absorption signal found at 1717.50 cm⁻¹ is situated within the wave number range of 1780-1610 cm⁻¹ and reflects the presence of double bonds in naphthenes with varying intensity. The IR absorption signals near 1500 cm⁻¹ in the spectrum provide additional insights into our previous analyses. Particularly, the signal at 1458.01 cm⁻¹ displays the deformation vibrations of the  group, typical of alkanes at medium intensity, along with the  group from naphthenes, demonstrating weak deformation vibrations. Additionally, another signal region is present at 1377.73 cm⁻¹, showing variable intensity attributed to the deformation vibrations of alkanes. The spectrum also indicates the presence of the  (methyl) group.

The analysis of the IR spectrum indicates that the liquid fraction obtained from low molecular weight polymer waste is primarily consists of of long-chain alkanes (classified as polyalpha olefins) and naphthenes (naphthenic hydrocarbons formed through the conversion of ethylene to cycloalkanes using added cyclohexane and Ziegler-Natta catalysts) as well as derivatives featuring double bonds.

Conclusion. The absence of signals in the spectrum's absorption region above 3000 cm⁻¹ indicates that there are no organic compounds containing the  group (where  can represent elements like oxygen, nitrogen, and others combined with hydrogen detectable in this wavelength range), specifically organic alcohols and naphthenic acids. Consequently, this indicates that it won’t lead to corrosion of metals when used as a dispersion medium in plastic molding materials. Based on the chemical analysis of the research object (low molecular weight polymer waste) and the results from its IR spectrum analysis, it was established that the material contains liquid naphthenic hydrocarbons and polyalpha olefins.These naphthenic hydrocarbons, found in the liquid fraction obtained through filtering the low molecular weight polymer waste, have a lower viscosity than the polyalpha olefins, leading to a reduction in the viscosity of the entire mixture.

References:

1. Chiqindilarni qayta ishlash: dolzarb muammo va takliflar. Xalq soʻzi, onl-line. 01 2022 yil.
2. Тиллоев, Л. И., Усмонов, Х. Р. У., & Хамидов, Д. Г. (2020). Техническая классификация отходов в газовых химических комплексах. Universum: технические науки, (5-2 (74)), 74-78.
3. Tilloev, L., Dustov, K., Alimov, A., Bobokulov, F., & Ruziev, F. (2021, April). Research the content of waste (yellow oil) of the shurtan gas chemical complex in Uzbekistan. In Journal of Physics: Conference Series (Vol. 1889, No. 2, p. 022057). IOP Publishing.
4. Преч Э., Бюльманн Ф., Аффольтер К. Определение строения органических соединений. Таблицы спектральных данных = Structure Determination of Organic Compounds. Tables of Spectral Data / Пер. с англ. Б. Н. Тарасевича. — Бином. Лаборатория знаний, 2006. — С. 251—318. — 1500 экз. — ISBN 5-94774-572-0.
5. Xamidov, D. G. A., & Temirov, A. H. O. G. L. (2020). PARAFINLI NEFTLARNING FIZIK-KIMYOVIY XOSSALARI TAHLILI. Science and Education, 1(9), 30-36.
6. Jumayev, A. V. O. G. L., & Xamidov, D. G. A. (2022). Maydalangan silikagel kukunini plastik surkov moylari tarkibiga qo’shish va xossalariga ta’sirini o’rganish. Science and Education, 3(6), 361-366.
7. Хамидов, Д. Г., & Базаров, Г. Р. (2017). Физико-химические основы процесса депарафинизации нефтепродуктов. Вопросы науки и образования, (3 (4)), 29-30.